Research indicates that Purging Disorder (PD), a newly specified eating disorder characterized by recurrent purging after normal or small amounts of food in normal weight individuals, is psychologically and biologically distinct from normality and Bulimia Nervosa. The broad, long-term goals of this research are to improve understanding of affective, cognitive, and somatic factors in the maintenance of PD so that effective treatments may be developed for this syndrome. Current explanatory models of disordered eating focus on antecedent factors that trigger a behavior and the psychological consequences that follow. Previous studies suggest that negative affect (NA), shape/weight concerns, stomach discomfort, and violation of dietary rules may play an important role in the propensity to purge among women with PD. However, research on PD has been limited to cross-sectional designs that cannot establish temporal sequences, retrospective self-reports that are subject to memory problems and cognitive biases, and laboratory-based studies that lack ecological validity. The proposed research addresses these limitations by using Ecological Momentary Assessment (EMA), a design that involves repeated assessments of current psychological states in participants'daily living environments. The specific aims of this study are to 1) identify proximal antecedents of purging, 2) identify consequences of purging, and 3) examine personality and comorbid psychopathology as moderators of associations between posited antecedents and purging behavior. Women with PD (N=35) will be recruited to carry palmtop computers and make multiple ratings per day for two weeks. Multilevel model analyses will be used to test study hypotheses that 1) increases in NA, shape/weight concerns, stomach discomfort, and violation of dietary rules predict purging behavior, 2) decreases in NA, shape/weight concerns, and stomach discomfort follow purging behavior, and 3) higher levels of impulsivity and current anxiety disorders enhance the association between posited antecedents and purging behavior. PUBLIC HEALTH RELEVANCE: The proposed study will be the first application of EMA to PD and thus represents highly novel research that will allow the examination of temporal associations between changes in affective, cognitive, and somatic factors and changes in purging behavior. These data are crucial to understand why women with PD purge after consuming normal or small amounts of food and may point to specific targets for the development of effective interventions. Currently, there are no evidence-based treatments for PD, a prevalent syndrome associated with significant psychosocial and medical morbidity. Thus, findings from the proposed study have the potential to significantly improve public health.